Dolphins and sharks prey on a school of mackerel off the Azores

Thousands of fish swarm into a huge shimmering ball - making a last desperate play for survival against an onslaught of dolphins and sharks. British Wildlife photographer Christopher Swann swam in the midst of this frenetic battle of life and death to capture these images off the coast of the Azores in the Atlantic Ocean.Picture: Christopher Swann/SPL/Barcroft Media